Author Archives: mathscinotes

Interesting Historical Note About Cheese

Posted on 27-February-2013 by mathscinotes

Interesting Historical Note About Cheese I like blog posts that go into the history of common things. This post does a nice job discussing cheese and its long history.

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Battery Freezing Math

Posted on 26-February-2013 by mathscinotes

I live in a cold climate -- so cold that under certain circumstances we can freeze our lead-acid batteries (Figure 1). A customer who lives in my region called recently and was wondering if I thought any of his batteries would have frozen over the winter. A number of his Internet service subscribers have vacation homes that are unoccupied over the winter. All of these vacation home owners turn off their AC power for the winter. Since all of our Optical Network Terminals (ONT) are connected to Uninterruptible Power Sources (UPS), they will begin operating off of their battery when the AC power goes away. If the home owner does not disconnect the battery, the ONT will run discharge the battery. This is important because a discharged battery will freeze -- a charged battery will not freeze. A battery that has been frozen is very likely a dead battery. Continue reading →

Posted in Batteries, Electronics | Tagged , , | 17 Comments

Russian Meteor Characteristics

Posted on 20-February-2013 by mathscinotes

A meteor exploded over Chelyabinsk, Russia (Figure 1), at 3:20 UTC on February 15, 2013. I have been reading accounts of the size, speed, and energy of the meteor. This post presents some simple calculations that verify the consistency of the expert's estimates on the meteor characteristics. Also, I thought it would also be interesting to look at the amount of overpressure required to cause the sort of damage that was seen after the meteor and to include some explanatory material as to how scientists determine the characteristics of a meteor. Continue reading →

Posted in Astronomy, Electronics | 1 Comment

Battery Outgassing Math

Posted on 12-February-2013 by mathscinotes

I recently have received a number of questions about the outgassing of hydrogen gas that can occur from lead acid batteries when they are being overcharged. I thought it would be useful to review what is happening when a battery is outgassing. When being charged, batteries can release enough hydrogen gas to create an explosive hazard. Consider this report and Figure 1 as an example as to what can happen. With lead-acid batteries, hydrogen gas can be generated any time, but charging is when the greatest challenges are faced. Continue reading →

Posted in Batteries, Electronics | 20 Comments

AC Backup Power Using A Simulated Sine Wave

Posted on 3-February-2013 by mathscinotes

Quote of the Day Whenever you want to marry someone, go have lunch with his ex-wife. - Shelly Winter Introduction A customer today requested an AC-output Uninterruptible Power Source (UPS) for our indoor Optical Network Termination (ONT) products. Product Management … Continue reading →

Posted in Electronics | 5 Comments

Great discussion of Saturn's Polar Hexagon

Posted on 2-February-2013 by mathscinotes

This particular post discusses a very interesting laboratory experiment that illustrates how the hexagonal region at Saturn's pole may form. Continue reading →

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Age Distribution of US Health Care Expenditures

Posted on 25-January-2013 by mathscinotes

I have been wondering why US health care costs are so high. I just read this report that claims that the US spends a far greater percentage of its health care dollars on the elderly than other countries. I decided to plot the data from the report myself to make viewing the data a bit easier -- see Figure 1. The expenditures are normalized to the costs for people in the 50 to 64 year old age range (arbitrarily given a value of 1 unit). Continue reading →

Posted in Financial | 4 Comments

Great Article on Recreating Shackleton's Whiskey

Posted on 19-January-2013 by mathscinotes

While I am not a drinker, I do admire the impressive technology that Scottish distillers used to duplicate the lost recipe for Shackleton's whiskey. They were even able to identify where the peat used in its formulation came from. Continue reading →

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Fond Memories of Fast-Moving Milk Bottles and Toy Boats

Posted on 19-January-2013 by mathscinotes

Last night on "How It's Made" they were showing machines filling bottles with a beverage. This show stimulated my memories from first-grade when I was shown a 16mm movie about how milk came to our door every morning. I still can remember almost every detail of this movie. The story started with a cow eating grass and ended with a bottle of milk on a kitchen table. What really caught my eye was the filling of the milk bottles by machines. It seemed like magic the way the bottles were put into a fast-moving row, filled while moving in a circle, and then capped. Continue reading →

Posted in General Science, Osseo, Personal | 1 Comment

The Joys of Electrostatic Discharge

Posted on 7-January-2013 by mathscinotes

I had to laugh at this Youtube video this morning. This poor guy shows you exactly how NOT to handle hardware during ElectroStatic Discharge (ESD) tests. Continue reading →

Posted in Electronics | 3 Comments